10Food ChainThe relationship between plants and animals that shows who eats what. Energy is transferred from one organism to another through the food chain
11Food WebA model of feeding relationships, describing the connections among all food chains within an ecosystem
12Energy PyramidA representation of the loss of useful energy at each step in a food chain
13Pyramid of NumbersBased on the number of organisms needed to make a simple food chain. Shows how large populations of certain organisms are needed to support very small populations of other organisms.
14SymbiosisAn interactive association between two or more species living together; may be parasitic, commensal, or mutualistic. The relationship between two organisms
15CommensalismA symbiotic relationship in which one species benefits and the other is not affected
16ParasitismA form of symbiosis in which the population of one species benefits at the expense of the population of another species
17MutualismA symbiotic interaction between two species in which both derive some benefit
18CompetitionOne of the biological interactions that can limit population growth; occurs when two species vie with each other for the same resource
19PopulationAll the organisms that belong to the same species living in a community
20CommunityAll the populations of different species that live in an ecosystem
21HabitatPlace where an organism lives and that provides the types of food, shelter, moisture, and temperature needed for survival
22NicheAn organism’s place in the ecosystem: where it lives, what it consumes, what consumes it, and how it interacts with all biotic and abiotic factors. A unique ecological role of an organism in a community.